Gemini-GRACES high-quality spectra of Kepler evolved stars with transiting planets

JOFRÉ, E. ; ALMENARA, J.M. ; PETRUCCI, R.; DÍAZ, R. F.; GÓMEZ MAQUEO CHEW, Y. ; MARTIOLI, E. ; RAMÍREZ, L. ; GARCÍA, L. ; SAFFE, C.; CANUL, E. F. ; BUCCIONO, A. ; GOMEZ, M.; MORENO HILARIO, E.

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2020 vol. 634 p. 29 - 29

0004-6361

ims. Kepler-278 and Kepler-391 are two of the three evolved stars known to date on the red giant branch (RGB) to host multiple short-period transiting planets. Moreover, the planets orbiting Kepler-278 and Kepler-391 are among the smallest discovered around RGB stars. Here we present a detailed stellar and planetary characterization of these remarkable systems. Methods. Based on high-quality spectra from Gemini-GRACES for Kepler-278 and Kepler-391, we obtained refined stellar parameters and precise chemical abundances for 25 elements. Nine of these elements and the carbon isotopic ratios, 12^C/13^C, had not previously been measured. Also, combining our new stellar parameters with a photodynamical analysis of the Kepler light curves, we determined accurate planetary properties of both systems. Results. Our revised stellar parameters agree reasonably well with most of the previous results, although we find that Kepler-278 is 15% less massive than previously reported. The abundances of C